U.S. Department of Justice officials began meeting with Chicago police on Wednesday, three weeks after the release of a video showing a white officer shooting a black teen 16 times, which spurred calls for Mayor Rahm Emanuel to resign.

The meeting is to review policies and procedures, a police spokesman said. The U.S. Justice Department said last week it would look at the department’s use of deadly force, among other issues.

Use of force by police has become a focus of national debate due to a series of high-profile police killings of black men by mainly white officers in U.S. cities. Baltimore police also are under federal scrutiny, after the death of a black man injured in police custody.

The Chicago Police Department “pledges the city’s complete and full cooperation,” said police spokesman Anthony Guglielmi. Those meeting with federal officials include Interim Superintendent John Escalante and command staff.

The October 2014 video showed Officer Jason Van Dyke shooting 17-year-old Laquan McDonald while McDonald appears to be walking away, and continuing to fire while the teen was on the ground. Van Dyke was charged with murder on Nov. 24, the same day the video was released.

Protesters have questioned why it took 13 months for the city to release the video and for a murder charge to be filed by Cook County State’s Attorney Anita Alvarez.

Sixteen protesters were arrested on Tuesday night, and all were charged with misdemeanors and released, according to Chicago police Officer Jose Estrada. Estrada said protesters were lying down in the street.

A protest is planned for Christmas Eve on the city’s “Magnificent Mile,” its most prestigious shopping district, according to the political group “Coalition for a New Chicago.” A Nov. 27 protest on the strip drew thousands of demonstrators, who prevented shoppers from entering some stores.

“We’re going to do prayer and demonstration,” said Gregory Livingston, Coalition founder. He said the group is also planning a protest at politicians’ offices on Thursday.

Also on Wednesday, the Chicago Justice Project, a nonprofit dedicated to transparency in local justice systems, sued Alvarez for denying Freedom of Information Act requests. Sally Daly, a spokeswoman for the prosecutor’s office, said officials had not yet read the lawsuit and could not comment.

Emanuel has responded to the criticism by firing his hand-picked police superintendent, Garry McCarthy, and replacing the head of the Independent Police Review Authority, which investigates police misconduct.